Card mounted photographs
from the 19th and early 20th century, such as cartes-de-visites, cabinet cards
and stereographs can be generally dated by their format and mount type. Printed
mount notations such as photographer's identification and title are fairly
reliable, but can still provide false information.

Dating by mount
type and style provides a rough indicator for identifying images. The caveat
is that many photographers, particularly in more remote areas, failed to keep
up to photographic fashion and used old mounts until their stocks were exhausted.
Also, photographers reprinted historically or commercially important images
long after they were originally taken. Also negatives were often sold
or copied and the mount information may not accurately reflect the history
of the images. For example, D. P. Flanders views of Prescott taken in the
Spring of 1874 appear on Williscraft mounts in the late 1870s and Continent
mounts into the mid 1880s

Notations on the
mounts can occasionally provide additional information about the image, but
should always be verified by other sources before being relied on. Handwritten
notations are the most suspect, often being added long after the image was
made by persons with only secondary knowledge.

The following
information is provided to assist in verifying possible image dates using
information based on the type and style of the photographic mount.